To establish a technique for stably formulating an isoquinolin-6-amino derivative as an ophthalmic agent or the like. A pharmaceutical preparation is provided including an aqueous composition containing a compound represented by the following formula (1)(in the formula, R1 and R2 each independently represent a hydrogen atom or a C1-C4 alkyl group, R3 represents a hydrogen atom or a hydroxy group, and "A" represents-CH(R4)- or -CH2-CH(R4)- (wherein R4 represents an optionally substituted C6-C10 aryl group, or an optionally substituted 5 to 10-membered heteroaryl group), and the formula (1) also includes a tautomer thereof) or a salt thereof or a solvate thereof, the aqueous composition being housed in a package which blocks a light having a wavelength of from 320 to 380 nm.
